As existing reserves of conventional light liquid hydrocarbons such as light crude oil are depleted and prices for hydrocarbon products continue to rise, new sources of hydrocarbons are desirable. Viscous hydrocarbons such as heavy oil and bitumen offer an alternative source of hydrocarbons with extensive deposits throughout the world. In general, hydrocarbons having an API gravity less than 22° are referred to as “heavy oil” and hydrocarbons having an API gravity less than 10° are referred to as “bitumen.” Although recovery of heavy oil and bitumen present challenges due to their relatively high viscosities, there are a variety of processes that can be employed to recover such viscous hydrocarbons from underground deposits.
Many techniques for recovering heavy oil and bitumen use thermal energy to heat the hydrocarbons, thereby decreasing their viscosity and increasing their mobility within the formation. This enables the extraction and recovery of the hydrocarbons. Accordingly, such production and recovery processes may generally be described as “thermal” techniques. A steam-assisted gravity drainage (SAGD) operation is one thermal technique for recovering viscous hydrocarbons such as bitumen and heavy oil. SAGD operations typically employ two vertically spaced horizontal wells drilled into the reservoir. Steam is injected into the formation via the upper well, also referred to as the “injection well,” to form a steam chamber that extends radially outward and upward from the injection well. Thermal energy from the steam reduces the viscosity of the viscous hydrocarbons, thereby enabling them to flow downward through the formation under the force of gravity. The mobilized hydrocarbons drain into the lower well, also referred to as the “production well.” The hydrocarbons collected in the production well are produced to the surface with artificial lift techniques.
Other processes use conductor-in-conduit heat sources to mobilize the heavy oil and bitumen, such as the processes described in U.S. Pat. No. 7,004,247 to Cole et al.
Other examples of hydrocarbon recovery processes are described in U.S. Pat. No. 7,673,681 issued on Mar. 9, 2010 to Vinegar et al., U.S. Publication No. 2011/0048717 published on Mar. 3, 2011 to Diehl et al., PCT Publication No. WO 2010/107726 published on Sep. 23, 2010 to Al-Buraik, and Canadian Patent No. 2,120,851 issued on Aug. 22, 1995 to Yu et al.